Chief of Staff Gen. Mark Welsh morphed into airpower incarnate — by donning a Captain America mask featuring a huge “A” — during a Sept. 17 speech at the Air Force Association’s Air and Space Conference.

“The ‘A’ is for ‘airpower,’ and don’t you forget it,” Welsh said to big laughs from the audience.

Welsh spoke about the importance of airmen and airpower. Right before putting on the mask, he showed the audience a video that concluded with the words, “Airpower: Without it, you lose.”

Welsh only wore the mask for a few minutes, but pictures of him in the mask have gone viral online. One such picture posted on Military Times’ “Line of Sight” blog was “liked” at least 1,200 times.

Some responses posted under the photo on Air Force Times’ Facebook page were snarky.

“Swing and a miss,” William Zeck wrote.

Commented Sean Baber: “So, I am supposed to council airman on respecting their uniform and wear it correctly, but 4 stars are walking around with masks on ... got it.”

Still others joked about Welsh being out of uniform regs and suggested replacing a rule to wear blues to work on Mondays with a new rule for “Costume Fridays.”

Other commenters appreciated a little humor in his speech.

“They can’t win can they?” wrote Kevin Crowley Maeder. “Airmen are going to complain that leadership is too rigid and then they show a little fun and used a prop to show a point and OMG they are disrespecting the uniform.”

The mask was but a small part of Welsh’s speech. As has become tradition, he spent a great deal of time paying tribute to exceptional airmen. He asked each to stand as he told his or her story. Then, he moved on to the importance of airpower — and the mask.

“The sad part about this is, last night, I put this thing on late at night — I was debating whether to do this — and I got distracted by something; about 30 minutes later, I realized I was still wearing it,” he said, getting a round of applause from attendees.